Lake Superior

Photo by Eric Epstein
- WDNR

Definition

General natural community overview

Lake Superior is a unique and vast resource of fresh water covering 31,700 square miles. It is the largest freshwater lake in the world by surface area and has 156 miles of coastline in Wisconsin. The lake is primarily cold water with summer maximum water temperatures below 22 degrees Celsius (72 degrees Fahrenheit). Lake Superior is relatively infertile with a historic fish fauna that consisted primarily of lake trout, ciscoes/whitefishes, and sculpins. Warmer and more fertile harbors and bays (e.g., Chequamegon) had a more diverse assemblage of cool and warmwater fishes, especially in the Perch family. Now the biota is dominated by introduced or invasive non-native species. Due to extirpations in other lakes, Lake Superior supports the last remaining Great Lakes population of two whitefish relatives - kiyi and shortjaw cisco.

Lake Superior has not experienced the same levels of development, urbanization and pollution as the other Great Lakes. Although Lake Superior is the cleanest and most healthy of all the Great Lakes, it is still threatened by toxic pollutants that bioaccumulate in the food chain and persist in the environment. These substances can be transported long distances in the atmosphere and end up in the lake. Local sources contribute pollutants to air and water, adding to the pollutant load entering Lake Superior. Because of its long retention time (191 years), pollutants entering Lake Superior can remain in the lake for over a century before draining to the lower Great Lakes.

Rare animals

Species of Greatest Conservation Need

The following Species of Greatest Conservation Need are listed according to their level of association with the natural community type, based on the findings in Wisconsin's 2015 Wildlife Action Plan.

Rare plants

The Natural Heritage Inventory has developed scores indicating the degree to which each of Wisconsin's rare plant species is associated with a particular natural community or ecological landscape. This information is similar to that found in the Wildlife Action Plan for animals. As this is a work in progress, we welcome your suggestions and feedback.

Major (3 on map)A major opportunity for sustaining the natural community in the Ecological Landscape exists, either because many significant occurrences of the natural community have been recorded in the landscape or major restoration activities are likely to be successful maintaining the community's composition, structure, and ecological function over a longer period of time.

Important (2 on map)Although the natural community does not occur extensively or commonly in the Ecological Landscape, one to several occurrences do occur and are important in sustaining the community in the state. In some cases, important opportunities may exist because the natural community may be restricted to just one or a few Ecological Landscapes within the state and there may be a lack of opportunities elsewhere.

Present (1 on map)The natural community occurs in the Ecological Landscape, but better management opportunities appear to exist in other parts of the state.

Threats/Actions

What are conservation actions?

Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the WWAP because lack of information can threaten our ability to successfully preserve and care for natural resources.

Photos

Freshwater estuaries are important features of the southwestern Lake Superior coast. The diverse wetlands associated with these drowned river mouths provide habitat for many rare plants and animals.

Photo by Eric Epstein.

Lake Superior estuary, Ashland County.

Photo by Eric Epstein.

Note: photos are provided to illustrate various examples of natural community types. A single photograph cannot represent the range of variability inherent in a given community type. Some of these photos explicitly illustrate unusual and distinctive community variants. The community photo galleries are a work in progress that we will expand and improve in the future.